I am standing on the steps of a grand staircase in Asgard, home of the hammer-wielding superhero Thor, played with deadpan charm and a stately English accent by Chris Hemsworth. This is a bustling intergalactic metropolis, with lustrous buildings reaching toward the heavens and sweeping terraces glistening beneath majestic skylines.

Or at least it will be. I’m in a town square, surrounded by retro huts and buildings lined with green vines and red roses, but the place is sparse and unpopulated: just me and a handful of others investigating the scenery. On top of most edifices are large sheets of blue material, which, I am told, are “digital extensions” – empty canvasses that will be adorned in the editing room with CGI skylines. The cutting-edge magic of the movies will transform this unpromising environment into the gleaming world of Thor: Ragnarok.

Making this vision even stranger is the presence of a giant rollercoaster looming above us. We are at Village Roadshow Studios in the Gold Coast in Queensland, Australia, in a part of town that usually attracts movie fans rather than movie-makers. Next door is an amusement park, Warner Bros Movie World, to which the rollercoaster belongs.

The director of Thor: Ragnarok is Taika Waititi, the New Zealander beloved in his home country for helming the two biggest homegrown successes in NZ box office history: Boy and Hunt for the Wilderpeople. Waititi, dressed in skinny jeans and faded Guns N’ Roses T-shirt, jokes that it’s hard to concentrate during production meetings because of the screams of thrillseekers being slammed up and down the rollercoaster.

Ragnarok’s production designer, Dan Hennah, who designed Peter Jackson’s Lord of the Rings and Hobbit movies, escorts us to another huge, vacant set. This one has a kooky, jumbled aesthetic, like a giant McDonald’s playground but painted with a washed-out colour palette. On screen it will be an alien planet called Sakaar. Hennah estimates that “maybe a quarter” of the movie takes place here, a “shanty town” populated by “aliens of all different sorts”. You come here, he explains “if you’re flying around in space and you hit one of those wormholes”. Spend a few hours on the set of a Thor movie and such space-fantasy talk soon feels run of the mill.

We get none of that when we meet Cate Blanchett. Asked who her favourite superhero is, the eminently sensible two-times Oscar winner responds: “Anyone in the world who’s overcoming adverse conditions is my superhero. Someone who, against all odds, maintains hope.” Does working on a superhero movie makes her feel at all like a superhero herself? “No. It’s no different from being a working mother in any industry.”

Blanchett plays Hela – Marvel Studios’ first major female supervillain – and she is virtually unrecognisable in the film: nu-goth get-up, long straightened hair, half a pound of mascara and a soul-piercing glint in her eyes.

Her outfit was conceived in a cluttered warehouse crammed full of mannequins, busts and fabrics. The costume designer, Mayes C Rubeo, is a veteran of big-name sci-fi productions including Avatar, John Carter and Warcraft.

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“We take pride that the armour of the main characters is made in-house – the old-fashioned way,” Rubeo says, as half a dozen colleagues around her busy themselves with sewing machines and fabrics. The costume designer talks excitedly about the “Scrapers”, who she says are people “that live in the wastelands of Sakaar”.

Waititi looks calm but very much in charge on set, directing Hemsworth and Tom Hiddleston on a large outdoor sound stage. The film’s executive producer, Brad Winderbaum, explains that this “is the mid-finale”. He adds: “We’ve got a giant, epic, Ragnarok-scaled finale in this film. One of the biggest climactic set pieces we’ve done to date as a studio. Thor goes on this grand cosmic adventure, and by the time it all wraps up in the end, you have elements from every single place he’s been, every character he’s interacted with.”

Waititi tears himself away from his production team to elaborate. “One of the things this movie will do is incorporate the natural beauty of Queensland,” he tells us. Someone rushes up to him clutching a folder containing a selection of images. After some contemplation, Waititi points: “That one.” Then to us: “See? This directing thing is easy.”

In between takes, Hemsworth stands around and performs bicep curls with weights larger than Thor’s hammer. Hiddleston, who plays arch-nemesis Loki, is in high spirits, bobbing up and down on the spot, his long black hair blown by an industrial size fan. Extras walk around in poncho-like robes, a few nursing baby dolls.

We meet the two inside a large cafeteria. Inevitably, given the planetary biceps we are confronted with, conversation soon turns to Hemsworth’s diet and fitness regime. “Lots of clean protein, lots of vegetables,” he says. “I’m on a very strict diet, and pretty strict workout programme.”

Hiddleston jumps in. “Nobody ever gives him enough credit for this,” he says, turning to his co-star. “Seriously, you’ve been here since what time? He’s been on set working as an actor all day, and then he has to go and train afterwards. There’s not many people who can do that.”

After talking of their excitement at working with Waititi the two say goodbye, and we return to the set to watch another couple of hours of filming.

As the buzz of activity continues, my mind returns to the unusual stillness of those vacant sets we visited in the morning: the places that post-production whizzbangery will transform into a fully-realised Asgard and Sakaar. Will they still be recognisable on the screen? My thoughts are interrupted by the sound of screams coming from somewhere above. At least this much is certain: the rollercoaster won’t make final cut.